Having a phone or tablet that a laptop cannot charge is extremely annoying. My tablet won't charge in any USB port on my laptop, regardless of any other things removed or added.
Add this small thing in series, and voila - now works.
This tells your laptop that the device is now a master (normal is a slave), which allows more current to be drawn. This is enough to allow the tablet to charge.
Please note, not all devices will work. A friends doesn't work, but the device is old and crappy so who knows. Either way for the $16 to be able to charge from a laptop any device that before you can't - really it's a savings.
For those traveling trying to keep cord and peripheral count down, this is so easy.

Verified that the uCharger was indeed helping pull more power using a Centech USB Power Meter. The improvement in charging speed will vary depending on how much extra power the system actually grants, but will more than likely to be quicker than just a direct connection.